Computer systems of the above-mentioned type are widely known in the field of information technology systems. In particular, most computer systems that can be electronically switched on and off are usually provided with an auxiliary voltage in a so-called “soft-off” or “standby” state. In this way, reactivation of the computer system, for example, by a timer, a key of the keyboard or a remote request, is enabled. Consequently, at least some components of a computer system remain powered at all times.
However, in exceptional circumstances such as power outages or unintended interruption of an AC supply line, the provision of the auxiliary voltage will be stopped. To enable an automatic restart of the computer system, a chipset may detect the interruption of an operating voltage. Furthermore, many firmware components such as BIOS programs, allow the automatic entering of a predefined operating mode of a computer system upon a first provision of an operating voltage. For example, many computer systems provide a firmware setting that defines an operating state according to the ACPI standard to be entered upon power-up.
However, despite the mechanisms described above, known systems suffer from several drawbacks. In particular, they do not ensure that the AC failure is detected in all operating states of the computer system. For example, if a relatively short power outage occurs during initialization of a computer system, the auxiliary voltage may not be interrupted. However, in this case some components of the computer system such as the chipset of a system board may not detect the presence of an AC failure. Furthermore, if an operating voltage is interrupted for some components, but not interrupted for another component, the computer system may end up in an undefined state. For example, a power supply unit that has already received a command to start up may not complete the startup operation if, during the start-up operation, an externally supplied AC supply voltage is interrupted. However, the chipset supplied with an auxiliary voltage may not become aware of the AC failure. In this case, a chipset of a connected system board may wait an indefinite amount of time for the provision of a good power signal by the power supply unit. This may result in a “hanging” computer system, i.e. a deadlock situation.
In these situations, a manual restart of the computer system, for example, by pressing a reset button or by disconnecting the computer system from the AC supply voltage for a prolonged period of time may be required to successfully restart the computer system. Such manual restart operations can result in relatively high maintenance costs, particularly in integrated computer systems installed at remote locations such as ATMs, self-service terminals or control computers.
For at least the reasons mentioned above, there is a need for improved systems and methods of detecting AC failure in computer systems.